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Hot, dry conditions can mean thirsty trees

As Michigan’s dry spring progresses into summer, the Michigan Department of Natural Resources suggests more than the lawn might need water.

Those who planted new trees this spring or last fall need to make sure they get their share as well during this stretch of warmer weather with little precipitation, the DNR advised.

“Abnormally hot and dry conditions mean your newly planted trees are probably thirsty,” said Kevin Sayers, the DNR’s Urban and Community Forestry Program manager. “Make sure any trees planted in the past year are getting at least 10 to 20 gallons of water a week until regular precipitation returns. Your trees will appreciate the drink.”

New trees, especially, are still setting their roots and need water, Sayers said. However, dry weather also can weaken healthy trees and make them more vulnerable to disease, insect damage or winter breakage.

Deciduous trees — those that lose their leaves in fall — show drought stress through curling or drooping leaves, according to the DNR. Leaves may “scorch,” or turn brown at the margins, fall off early or exhibit early fall color. Evergreen needles may turn yellow, then red or brown.

It’s important to water trees correctly. When watering, prioritize newly planted or high-value trees. Water newly established trees weekly and established trees every two to three weeks. A long, slow soak under the tree’s dripline — the ground where branches extend over — is best, so soil is saturated at least 10 to 12 inches deep, the DNR recommends. Once a week is generally enough. Overwatering can create problems as well, so if soil under the tree is moist, don’t add more water.

Mulch also helps retain soil moisture and save water. Apply 3 to 4 inches of organic mulch under the tree canopy, around but not touching the base of the trunk. You want the finished mulch pile to look like a doughnut, not a volcano.

Other tree watering tips from the DNR include —

— Sprinkler: Place an empty container or rain gauge nearby to measure about 1 inch of irrigation.

— Hand watering via hose: Let water run slowly until the ground is saturated, 10 to 12 inches deep, and moist near the base of small trees or at various points under the dripline of large trees.

— Five-gallon bucket: Most newly planted trees need 5 to 10 gallons of water per inch of trunk diameter (at knee height) each week.

— Soaker or trickle hoses: Saturate the soil under the dripline to at least 10 to 12 inches deep.

— Don’t water during the middle of the day. Much of the water applied at the hottest or windiest time of day is immediately lost to evaporation.

— Mist sprinklers aren’t effective for trees. As much as 70% of water may be lost to evaporation into the air.

— Lay off the fertilizer. Fertilizer salts can cause root injury when soil moisture is limited.

Summer is a stressful time to plant trees, largely due to hot temperatures and the need for water. So, if the tree hasn’t already been planted, it may be best to wait until fall.

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